Injury or disease leading to the loss of the use of the lower leg, including soft tissue and bone injury or disease, occur every day and lead to ambulation difficulties for the sufferer. Often, the damage is such that an individual should keep weight and pressure off of the injured limb for several weeks or months. In cases of severe injury or disease (such as diabetes), below-knee amputation may be necessary, in which case the use of the lower limb is permanently lost. Most individuals are able to utilize crutches during the period of rehabilitation, but use of crutches requires a basic level of upper body strength and the contact points between the crutch and the user can develop skin irritation and pain due to pressure. Moreover, a person who also suffers arm or shoulder weakness may need to utilize a wheelchair during rehabilitation.
In the case of below-knee amputation, patients who are not able to comfortably use or afford a socket-type prosthesis permanently need an alternative means of assistance for ambulation. Alternatively, patients who use a socket-type prosthesis may encounter situations when a socket-based prosthesis cannot be worn, such as for a period of time following amputation surgery while the residual limb is healing from the surgery, or when the use of a socket-type prosthesis must be discontinued to provide time to heal from socket-induced pressure sores and/or irritation.
Crutches and wheelchairs both present difficulties for users in navigating doorways, steps, slopes, getting in and out of automobiles, and the like. Crutches also present difficulties due to the loss of the use of the hands and arms, making the carrying of items and other basic functions quite difficult.
Crutchless ambulation devices have been proposed. For instance, U.S. Pat. Nos. 7,303,537, 6,494,919, 6,799,592, 7,600,524, and U.S. Patent Application Publication No. 2007/0251560 describe devices that may be coupled to an individual's leg with the leg held in a flexed position, so as to provide arm free ambulation and support for the injured limb. Unfortunately, such devices prevent any flexion and extension of the knee, leading to an awkward gait for anyone utilizing the devices.
What are needed in the art are limb prostheses for people suffering a lower leg injury or disease that provides for a more natural walking motion. More specifically, what is needed in the art is a limb prosthesis that allows the wearer to use the motion of their own knee to control their motion and maintain the freedom of the arms and hands of the user.